RV-14A operating experience.

rvbuilder2002 · #1 10-31-2014, 09:38 AM

In light of the number of negative comments in the past regarding the decision to choose the IO-390 as the focus engine for the RV-14, out of concern for it being a fuel thirsty engine, and the opinion that the airplane suffers in performance compared to an RV-7; I thought I would give an update on our experience now that we have been operating it for a while (airplane has surpassed 500 Hrs).
Having just made a 2000+ mile round trim to the Copperstate Fly-in, I can say that I never cease to be impressed by the airplane.
Yes I am probably a bit biased, but I think the feeling is entirely valid.
My wife has traveled with me a lot in RV's since we completed our first one in 1993.
This was her second long trip in the RV-14 and she could not stop talking about how much more comfortable she felt with the additional cockpit room. The baggage space and payload capability makes this type of trip much easier for us (we need to carry a lot of display materials and equipment with us).
At upper cruise altitudes (10,500 - 11,500) we got true airspeeds of 170 - 172 Kts while burning 8.7 - 8.8 GPH. This was while operating slightly lean of peak (.2 - .5 GPH).
We have flown the airplane quite a bit on trips along side of the RV-7A prototype. At lower altitudes the RV-7A is a little bit faster, but at higher altitudes the tide is turned and the higher aspect ratio wing and different airfoil turn the advantage to the RV-14A.

I think you RV-14 builders are really going to like this airplane......

Tom Martin · #2 10-31-2014, 10:18 AM

Happy wife, happy life.

ao.frog · #3 10-31-2014, 10:25 AM

Thanks for the report.

Just wondering: what was the powersetting at the 8.7 - 8.8 fuelburn?
Also: what the indicated percent power?

rvbuilder2002 · #4 10-31-2014, 10:59 AM

Quote:

Originally Posted by ao.frog

Thanks for the report.

Just wondering: what was the powersetting at the 8.7 - 8.8 fuelburn?
Also: what the indicated percent power?

2400 RPM / full throttle
MP at those altitudes/temps would be somewhere between 20 - 21 inches but I didn't take note of specifics (it will vary somewhat depending on air temp., etc.)
I didn't note the display % pwr, it is not displayed with our current screen configuration if you have the screen split 3 ways.

RV10inOz · #5 10-31-2014, 01:08 PM

Simple answer, 63% power.

Remember that WOT is the most efficient way to run the engine, the RPM where it is smooth, and when LOP fuel flow determines HP. So that was around 133HP.

I am perplexed at why anyone would be complaining. The 390 seems the obvious choice. The fuel burn issue for most people is only a problem because they either have never learned or refuse to learn how to operate them properly.

Scott was operating properly

Canadian_JOY · #6 10-31-2014, 01:48 PM

With respect to the IO390 being thirsty, the Glasair Sportsman has proven a good test bed to analyze this claim. This airframe can be built in the TWTT program with a 180hp IO-360, a 200hp IO-360, or the engine that most builders choose, the IO390. Performance comparisons between the engines reveal that, of course, the IO390 will move the airplane faster as a result of its greater available power, but that speed increase comes with a fuel burn increase commensurate with the increased horsepower being used.

In general, with the Sportsman, flying a 180hp IO-360 and a 210-hp IO-390 side by side at the same speed and density altitude will produce very similar fuel burns, plus or minus the small variations attributable to slight differences in the airframes and their rigging as well as differences in pilot technique.

In short, the IO-390 isn't a particularly fuel-thirsty engine, in and of itself.

flynwest · #7 10-31-2014, 02:06 PM

I have the 390 in my 8 and routinely burn less fuel than my buddies 8 with a fadec system, and I can out run him. I love my IO 390!

Mike H · #8 10-31-2014, 03:51 PM

Thanks for the information Scott. Stuff like this helps keep us builders motivated! Sounds like the perfect compromise in a two seat RV!

kamikaze · #9 11-01-2014, 08:10 AM

"negative comments in the past regarding the decision to choose the IO-390 as the focus engine for the RV-14"

Indeed ... one of the issues for me is not just the engine itself, but the lack of alternatives that will fit relatively easily in there. The XP-400 is the only one AFAIK.

Thing is these days there are plenty of engines like the IO-375, X-371 or X-409 that could also fit the bill ... if it weren't for the weight issue ...

Finally, the IO-390 is avgas only, an issue for some in north america, and an issue for everyone outside north america ... a strange choice from that point of view ... At least the XP-400 or whatever BPE will build for you can have mogas friendly low compression configurations ...

A FWF kit that will support the lighter engines (appropriate engine mount and cowl?) would certainly be a great seller I'd expect ...

This whole engine business is really driving me bonkers about choosing the RV-14!

RV7ator · #10 11-01-2014, 09:16 AM

Always interesting to receive a good report meeting expectations. But, Scott,
when the boys get done whipping up the taildragger version, immediately start fixing the one great shortcoming of the -14...utility.

A wife's happiness also has a proportional baggage component. The -14 desperately needs a baggage door to take advantage of the capacious baggage volume. It looks silly without one. It's a clumsy and awkward struggle up the wing with anything clunky and/or heavy, maybe passing it through the seat-roll bar gap in the bag area. Tip the seat forward and it's now in the way of stepping in. Try all this with a loaded, but melted ice, ice chest!

The tip-up slider on my -7 makes loading oh so easy. Stand on the ground and directly drop in The Big Bag. Maybe Van's can devise an open-able rear window. Something!

John Siebold
Boise, ID